Spiradenoma is a benign, morphologically well-defined cutaneous adnexal neoplasm that is closely related to cylindroma. We present the rare occurrence of adenoid cystic carcinoma (ACC)-like areas in 7 spiradenomas and 1 spiradenocylindroma, not described in the English literature to date. The ACC-like areas were a minor but significant component in all lesions and were usually multifocal and blended with the conventionally appearing parts of the neoplasms. The ACC-like areas were typified by cribriform formations of epithelial cells concentrically arranged around gland-like spaces filled with mucin, homogeneous eosinophilic material, or granular basophilic material. In some neoplasms, only mucin occurred in these pseudoglandular structures, whereas in other cases, a combination of all 3 secretory products was encountered. Although well-developed bilayered glands with a demonstrable peripheral myoepithelial cell layer were not recognizable in the ACC-like areas, immunohistochemistry demonstrated myoepithelial differentiation in these portions of the tumors. When present in the ACC-like areas, ductal structures manifested a rather squamoid lining, without a recognizable peripheral myoepithelial cell layer. It is concluded that the ACC-like pattern, although a rare feature and of no clinical consequence, is a distinctive finding in a minority of cases and extends the morphological spectrum of spiradenoma and spiradenocylindroma occurring sporadically or in the setting of Brooke-Spiegler syndrome. It represents a potential diagnostic pitfall, particularly in a limited biopsy specimen where the changes may be misdiagnosed as ACC.
From the *Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Pilsen, Czech Republic; †Dermatopathologische Gemeinschaftspraxis, Friedrichshafen, Germany; ‡Division of Tissue Pathology, PathWest Laboratory Medicine WA, Nedlands, Western Australia, Australia; §Department of Pathology, IRCCS-“Casa Sollievo della Sofferenza” Hospital, San Giovanni Rotondo, Italy; ¶Department of Pathology, Academy of Medical Postgraduate Education of Belarus, Minsk, Republic of Belarus; and ‖Bioptical Laboratory, Pilsen, Czech Republic.
Supported in part by the Internal Grant Agency (IGA) of the Ministry of Health of the Czech Republic (NS 9734).
Reprints: Dmitry V. Kazakov, MD, Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Alej Svobody 80, 304 60 Pilsen, Czech Republic (e-mail: firstname.lastname@example.org).